Microplastic leachates inhibit small-scale self-organization in mussel beds.

Self-organized spatial patterns are increasingly recognized for their contribution to ecosystem functioning. They can improve the ecosystem's ability to respond to perturbation and thus increase its resilience to environmental stress. Plastic pollution has now emerged as major threat to aquatic and terrestrial biota. Under laboratory conditions, we tested whether plastic leachates from pellets collected in the intertidal can impair small-scale, spatial self-organization and byssal threads production of intertidal mussels and whether the effect varied depending on where the pellets come from. Specifically, leachates originating from plastic pellets collected from relatively pristine and polluted areas respectively impaired and inhibited the ability of mussels to self-organize at small-scale and to produce byssal threads compared to control conditions (i.e., seawater without leaching solution). Limitations to natural self-organizing processes and threads formation may translate to a declined capacity of natural ecosystems to avoid tipping points and to a reduced restoration success of disturbed ecosystems.

Additives in polypropylene and polylactic acid food packaging: Chemical analysis and bioassays provide complementary tools for risk assessment.

Plastic food packaging represents 40 % of the plastic production worldwide and belongs to the 10 most commonly found items in aquatic environments. They are characterized by high additives contents with >4000 formulations available on the market. Thus they can release their constitutive chemicals (i.e. additives) into the surrounding environment, contributing to chemical pollution in aquatic systems and to contamination of marine organism up to the point of questioning the health of the consumer. In this context, the chemical and toxicological profiles of two types of polypropylene (PP) and polylactic acid (PLA) food packaging were investigated, using in vitro bioassays and target gas chromatography mass spectrometry analyses. Plastic additives quantification was performed both on the raw materials, and on the material leachates after 5 days of lixiviation in filtered natural seawater. The results showed that all samples (raw materials and leachates) contained additive compounds (e.g. phthalates plasticizers, phosphorous flame retardants, antioxidants and UV-stabilizers). Differences in the number and concentration of additives between polymers and suppliers were also pointed out, indicating that the chemical signature cannot be generalized to a polymer and is rather product dependent. Nevertheless, no significant toxic effects was observed upon exposure to the leachates in two short-term bioassays targeting baseline toxicity (Microtox® test) and Pacific oyster Crassostrea gigas fertilization success and embryo-larval development. Overall, this study demonstrates that both petrochemical and bio-based food containers contain harmful additives and that it is not possible to predict material toxicity solely based on chemical analysis. Additionally, it highlights the complexity to assess and comprehend the additive content of plastic packaging due to the variability of their composition, suggesting that more transparency in polymer formulations is required to properly address the risk associated with such materials during their use and end of life.

Microplastic leachates disrupt the chemotactic and chemokinetic behaviours of an ecosystem engineer (Mytilus edulis).

The massive contamination of the environment by plastics is an increasing global scientific and societal concern. Knowing whether and how these pollutants affect the behaviour of keystone species is essential to identify environmental risks effectively. Here, we focus on the effect of plastic leachates on the behavioural response of the common blue mussel Mytilus edulis, an ecosystem engineer responsible for the creation of biogenic structures that modify the environment and provide numerous ecosystem functions and services. Specifically, we assess the effect of virgin polypropylene beads on mussels' chemotactic (i.e. a directional movement in response to a chemical stimulus) and chemokinetic (i.e. a non-directional change in movement properties such as speed, distance travelled or turning frequency in response to a chemical stimulus) responses to different chemical cues (i.e. conspecifics, injured conspecifics and a predator, the crab Hemigrapsus sanguineus). In the presence of predator cues, individual mussels reduced both their gross distance and speed, changes interpreted here as an avoidance behaviour. When exposed to polypropylene leachates, mussels moved less compared to control conditions, regardless of the cues tested. Additionally, in presence of crab cues with plastic leachates, mussels significantly changed the direction of movement suggesting a leachate-induced loss of their negative chemotaxis response. Taken together, our results indicate that the behavioural response of M. edulis is cue-specific and that its anti-predator behaviour as well as its mobility are impaired when exposed to microplastic leachates, potentially affecting the functioning of the ecosystem that the species supports.

Identification and quantification of plastic additives using pyrolysis-GC/MS: A review.

Analysis of organic plastic additives (OPAs) associated to plastic polymers is growing. The current review outlines the characteristics and the development of (multi-step) pyrolysis coupled with a gas chromatography mass spectrometer (Py-GC/MS) for the identification and semi-quantification of OPAs. Compared to traditional methods, Py-GC/MS offers advantages like suppressing extensive steps of preparation, limiting contamination due to solvents and the possibility to analyse minute particles. Its key advantage is the successive analysis of OPAs and the polymeric matrix of the same sample. Based on the studied articles, numerous methods have been described allowing identification and, in some case, semi-quantification of OPAs. There is nevertheless no gold standard method, especially given the huge diversity of OPAs and the risks of interferences with polymers or other additives, but, among other parameters, a consensus temperature seems to arise from studies. More broadly, this review also explores many aspects on the sample preparation like weight and size of particles and calibration strategies. After studying the various works, some development prospects emerge and it appears that methodological developments should focus on better characterizing the limits of the methods in order to consider which OPAs can be quantified and in which polymers this is feasible.

A preliminary analysis of microplastics in edible versus non-edible tissues from seafood samples.

Plastics have been widely reported to be present in the environment yet there are still many questions regarding the extent of this and the impacts these may have on both the environment and human health. The purpose of this investigation is to determine levels of micro and mesoplastic (MP), in the 1-5000 µm range, in commercially important species of finfish and shellfish. Additionally, to determine and compare the relative MP levels in edible versus non-edible tissues, and consider the wider implications in terms of human health concerns with a preliminary risk identification approach. For several fish species, samples taken from typically non-edible (gills, digestive system) and edible (muscle) flesh, and were analysed separately. Scallops, where all tissues are edible, were analysed whole. Significant differences were observed in the number of particles isolated from the finfish gills and digestive tissues relative to the control samples, but not in the edible flesh. For scallops, the abundance of particles in the Scottish samples did not vary significantly from the control, while the Patagonian scallops displayed significantly higher numbers of MPs. Characterisation of MPs by FTIR microscopy found that 16-60% (depending on species) were polyethylene terephthalate (PET) and polyethylene (PE) in origin. The risk identification results validate MPs as an emerging risk in the food chain and establish seafood as a vector for the exposure and uptake of MPs through the ingestion route for humans. Levels of MPs in seafood, and a direct link to the human food chain, suggests that their quantification be included as one food safety measure.